Scorched earth: Wildfires will change the way we live

IF WE are lucky, an international climate agreement will be forged in Copenhagen later this year and emissions targets set in a bid to limit global warming to 2 °C above pre-industrial levels. Agreement in Denmark or not, I find the breezy way so many politicians and commentators talk as if such an increase were no big deal truly amazing. The truth is we have no idea what will happen at those places where you and I live if we raise the global thermostat 2 °C or more. Worse, there is another factor that could crank that thermostat still higher, making life quite as intolerable as the well-understood threat from rising sea levels&colon; fire.

The fossil record shows that fires started to occur soon after vegetation was established on Earth during the Silurian, about 420 million years ago. Ancient terrestrial life’s exposure to fire gives us good reason to think fire is an important evolutionary factor and, more controversially, that life co-evolved with fire.

Fire can be seen as a physicochemical process, a “fire triangle” of oxygen, fuel and heat for ignition. Combustion can occur if the concentration of oxygen is higher than 13 per cent, and variation in oxygen levels correlates with fire activity in Earth’s history. Fluctuations in atmospheric oxygen through geological time significantly affected fire risk. For example, in the Permian, oxygen levels were substantially higher than now, and even moist giant moss forests sometimes burned.

Those Permian coal fossils flag up another key detail&colon; the burial of decay-resistant charcoal and organic matter may have led to long-term reductions in the ...

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